1. Fields of the Invention
The present invention relates to a air pollution sampling system, especially to an active air pollution sampling system that combines with positioning devices such as a GPS, INS/GPS or INS/GPS/AHRS, Wi-Fi positioning etc. It could sample in wide area without use of a power source.
2. Descriptions of Related Art
Monitoring of air pollutants is an essential issue in monitoring and studies of a variety of fields such as human heath, environmental protection, industrial development, protection of historical monument, sustainable development and nuclear chemical or biological emergency response. Thus along with development and progress of environmental protection technology, people's concepts and requirements of environmental protection, new techniques and patents are developed continuously. For example, refer to U.S. Pat. No. 5,040,424 “High volume PM.sub.10 sampling inlet”, applied by Virgil A. Maple et al of the University of Minnesota in 1990, a sampling inlet removing the part of particles that are larger than 10 microns is revealed. Refer to U.S. Pat. No. 6,402,817 “Low pressure drop, multi-slit virtual impactor”, applied by Werner Bergman et al of the University of California in 2000, an inertia of particles suspended in air flow is increased by increasing speed of the air flow. Once the particles having an inertia greater than a given amount (a threshold), the particles with sufficient inertia don't move along with the direction of the air flow, and will impact on the flat surface directly and will be trapped in the receiving chambers. The airstream is accelerated to different levels gradually so as to classify particles suspended in the air. Refer to Chinese Pub No. 1695771 “Sampler for aerosol granules”, applied by Chen Xu et al of the Tsinghua University, this patent is also based on the inertia and impact. A plurality of particles with different aerodynamic diameters in air stream is collected and samples with sufficient amount and evenness are provided. Simultaneously, the stability of particles with various cut size are ensured. Moreover, refer to Chinese Pub. No. 1654944 “Radioactive aerosol granularity separating and sampling unit” applied by Lu Zhengyong et al, China Institute for Radiation Protection, utilizing the property that the size of RnTh daughter is smaller than the normal size of artificial aerosol to separate the natural and artificial nuclides. The interference to artificial airborne radioactivity measurement caused by RnTh could be reduced by the sampling unit. Refer to Taiwanese Pat. No. 1294034 “Sampling method for bioaerosol in air”, applied by Chin-Shin Lin of archilife research foundation in 2006, the bioaerosols in air such as allergens and fungus are sampled and analyzed for evaluating health risks. However, above prior arts are designed according to natures of the air pollutants.
Moreover, some inventions focus on progress of working forms. For example, refer to U.S. Pat. No. 6,167,766 “Programmable atmospheric sampling systems and method” applied by David L. Dunn et al. of Westinghouse Savannah River Company in 1997, a sampling system is revealed. The sampling system controller includes a control unit for management of a plurality of sampling chambers. Samples are acquired according to the timing and the flow rate controlled by program codes saved in a data module. Moreover, refer to Chinese Pub. No. 101231220 “passive atmospheric aerosol individual sampler” applied by Liu Wei et al. of Chinese Academy of Sciences in 2007, for individual research in microenvironment, a portable passive sampling apparatus different from conventional active sampling type and convenient for carrying is provided.
Furthermore, some other inventions put much emphasis on the integration of sample continuity and measurement instruments. For example, refer to Chinese Pub. No. 2884178 “A quick trap method for atmospheric particles” applied by Wang Yue-Si et al. of Chinese Academy of Sciences in 2007, all-weather sampling is achieved by membraneless sampling of suspended particles. Also refer to Chinese Pub. No. CN2856982 “Continuous sampling paper feeding integrated device for radioactive aerosol” applied by Zhang Zhilong et al. of China Institute of Radiation Protection in 2005, a continuous sampling paper feeding integrated device that can real-time monitor radioactive aerosol from nuclear facilities with increased utility and reliability is revealed.
Air samplers are divided into active type and passive type according to a control way of air flow that enters the sampler. The active type requires a power source (air pump) to withdraw the air and mostly takes samples at a fixed point. Thus the sample representativeness is lower. Although there are commercial portable air samplers available now, they are applied to monitoring of respiration of staffs. The sampling rate is close to respiration rate of staffs (2 L/min) so that it's not suitable for environmental air sampling (50 L/min). Once the active air sampler that requires power sources is loaded on a vehicle to perform air sampling at multiple locations with higher flexibility, the air sampling rate of air pump is affected by interference of gas turbulence generated during the movement of the vehicle. Thus the preset air sampling flow of the air pump is also affected and the volume of air samples is unable to be obtained correctly and precisely. Therefore, while performing air quality monitoring now, a plurality of air pumps is used to get air samples in a certain area. However, conventional active air sampling uses a air pump to take samples at a fixed point continuously and exhaust air at the same point. “The sampled air” can't be restricted and may be sampled again by the active air sampler. Thus the concentration of pollutants in the air samples will be diluted and then the sampling will loss the representativeness of samples.
Moreover, natural disaster surveys or emergency events that require environmental air sampling may occur at any position such as outdoors or city streets. Generally, most power for outdoor use is high voltage such as 380V power supply except special ones applied and obtained from electric power companies. Such a high voltage power supply is not suitable for a normal air pump to take air samples. In order to use outdoor powers, users need to prepare power converters. Thus it is difficult to get and inconvenient to use outdoor power sources. As to indoor power sources such as 110V, the power points are arranged inside the buildings so that the air pump is inconveniently connected with the power point by extension cords. Users have better to prepare generators for power supply of the air pump. Thus the conventional active air samplers are very labor and time consuming. It is disadvantageous to flexible sampling and the requirement of multi-point or wide area sampling is difficult to be satisfied. The passive-type air samplers depend on natural air circulation while its sampling rate is low and instability is high. Once the samplers are carried by staffs or moved along with vehicles, it's more difficult to estimate the sampled air volume. Such sampling way is suitable to long-term (over months, seasons and years) and static sampling works.
Thus the present invention designs an air pollution sampling system that uses a force generated by the movement of the vehicle as a power source to replace conventional air pumps so as to avoid trouble of the power source caused by the use of air pump. Without using power, the high flow active sampling is still achieved. Moreover, during the movement of the vehicle, the sampling flow of the flow meter and the sampling positions of the geographic positioning device are recorded automatically and precisely so as to achieve wide-area multi-point sampling and increase the representativeness of air samples. During the sampling period, the geographic positioning device such as GPS, INS/GPS, and INS/GPS/AHRS available can provide movement speed and even three-dimensional speed data of the vehicle. If there is an established correlation function between the air sampling flow rate and the vehicle speed, it could be input into a processing unit. The vehicle speed is converted into air sampling rate so that there is no need to use the flow meter. The cost for setting air pollutant samplers will be dramatically reduced. The air sampling point will be moved along with the vehicle so that the backflow and dilution problems of the air sampling taken at fixed points can be avoided. Once the vehicle stops moving, the air sampling will end immediately. The sample volume (or the sampling rate) along the sampling path distributes well and evenly on the area with the sampling points. And there is a special emphasis on that the air sampling system does not need to equipped with any air pump which can have large air sampling rate.
The samples are taken during the movement of the vehicle. The sampling system could be equipped with the vehicle before go into the sampling. The vehicle can be controlled remotely or driver, thus staffs responsible for air sampling don't need to set up the air pollution sampling system directly in the polluted environment and the risk of exposure to pollutants is reduced. Furthermore, an extended sample port and baffle plates are disposed in front of a filter so as to avoid interference cause by turbulence generated during the movement of the vehicle. However, the vehicle itself also disturbs the air surrounding. Thus the extended sample port is designed to avoid the air turbulence caused by the vehicle. In order to prevent rain drops or sands bumps from impact on the filter layer directly, the baffle plate is arranged in front of the sample port. The size and the angle of an opening of the sample port are adjustable to control air sampling flow. The sampling force of air relates to the movement speed of the vehicle and the positioning device can measure the vehicle speed. Thus even there is no flow meter, the sampling flow rate of air samples can be calculated according to the movement speed of the vehicle. The present invention further includes an information storage unit together with the geographic information system for data collection and integration so that the sample results can be used for following applications.